U.S. Pat. No. 4,979,791 issued Dec. 25, 1990, discloses an active device mount having a socket for receiving a holder for an optical fiber to be aligned with an active device, known also as an optoelectronic device, mounted in the holder. The holder is comprised of a ceramic, for example, alumina, having a light coloration. Ceramics are a class of materials useful for small precision parts requiring precise dimensions that do not vary appreciably with changes in temperature. Further, ceramics are generally hard substances, and are too hard for shaping by machining tools in widespread industrial use. Manufacturing operations for ceramic precision parts remain highly specialized and expensive, elevating the cost of such parts.
On the other hand, the active device mount can be constructed without unnecessary elevated cost by using materials more susceptible than are ceramics to being shaped by the manufacturing operations widely practiced. For example, stainless steel, a material of less exceptional properties than ceramics, is readily shaped by machining operations to provide a socket with adequate dimensional precision. One disadvantage is observed when the stainless steel has been in rubbing contact with a ceramic, particularly a ceramic of light coloration and inherent abrasiveness. Stainless steel does not itself become visibly marred by an unsightly stain of its own oxide. Yet stainless steel is capable of applying marks by rubbing upon lighter coloration ceramics. The stainless steel of the socket applies visible dark stains or marks upon the ceramic holder whenever the ceramic holder rubs against the socket during its insertion and withdrawal.